Electric pulse temperature-regulating device



Oct. 30, 1956 M. l.. A. BIDAULT ELECTRIC PULSE TEMPEEATUEE-REGULATING .DEVICE Filed March 30, 1951 2 Sheets-Sheet l llll Oct. 30, 1956 M. L. A. BIDAULT 2,768,792

ELECTRIC PULSE TEMPERATURE-'REGULATING DEVICE Filed March 30, 1951 2 Sheets-Sheet 2 ELECTRlC PULSE TEMiPERATURE-REGULATING DEVCE Marcel L. A. Bidault, Le Vesinet, France Application March 30, 1951, Serial No. 218,417

Claims priority, application France April 3, 1950 4 Claims. (Cl. 236-46) This invention relates to devices for regulating the temperature of air within an enclosure, and more particularly to such devices where the said enclosure is an airplane cabin.

An object of my invention is to provide a temperatureregulating device capable of maintaining a constant temperature within a sealed enclosure by a substantially continuous and gradual variation of the quantity of heat supplied by heating means to said enclosure.

A tempcinture-regulating device according to the invention comprises a bi-metal strip element subjected to the temperature to be controlled and one end of which is adapted to displace a contact element applied against the surface of a revolving member which includes over its surface area electrically-conductive sections to which curr-ent is applied non-conductive sections, said sec tions varying in their extent over said surface, in such a way that current is taken off by said contact element at each revolution of the revolving member for variable periods of time to provide a correspondingly variable electric output. This output is used for controlling the heating means.

in order that the bi-metal temperature-responsive element should be in thermal equilibrium with the air in the enclosure to be controlled, the said air is constrained by auxiliary means such as a fan to iiow around and through said temperature-responsive element.

Preferably the motor provided for driving in rotation the revolving member is made simultaneously to drive the said auxiliary means such as a fan which provides for the requisite air circulation in contact with the temperatureeresponsive element.

A better understanding of the invention will be had from the ensuing description and the accompanying drawings, it being understood that both the description and drawings are given for purposes of illustration and not of limitation.

Fig. l is a sectional view of a temperature-regulating device according to the invention;

Fig. 2 is a section on line li-ll of Fig. l;

Fig. 3 is a general diagrammatic view of an enclosure with means according to the invention for maintaining a predetermined constant temperature therein.

Fig. 4 shows a modification of the revolving member in the apparatus shown in Figs. l and 2;

Fig. 5 is an explanatory diagram of the operation of the device.

The temperattire-regulating device shown in Fig. l comprises a generally cylindrical casing 1 having mounted in the bottom thereof a helically-wound bi-metal strip element 2. The bimetal strip element is supported at opposite ends by two trunnions 3a and 3b rotatable in bearings secured to the casing l. rEhe free end of the trunnion 3a has an arm radially projecting therefrom and terminating in a contact or feeler portion 9a. The free end oi trunnion 3b carries a pinion lll for rotational adjustment of the bi-metal strip 2 through gearing 12--13 from adjusting knob 11.

The casing 1 contains an electric motor having a two-ended shaft 5 one end of which drives a fan 6. A par `tion 14 overiies the bi-rnetal strip 2 and cooperates with the casing l to dene a channel in which the bimetal strip is housed. This channel has an air-inlet aperture '7 formed in the casing wall and communicates at its right (as shown in Fig. l) with a gap defined ben vertical partitions l5 und 17 in the casing. The paron 17 is formed W h a wide opening through which the fan-shaft 5 projects from the motor i into an compartment defined between the partition 17 and the adjacent end-wall of the casing i, said end-compartment housing the fan 5. The end-compartment housing the fan communicates with the outside atmosphere through an aperture l. When the fan is rotated it draws iu air through inlet 7, around and through bi-metal strip and thence through the said gap between 15 and 17 and through the aperture in partition i7 into the endcompartment and out through the outlet 18 as indicated cy il e arrows.

The end of the shaft of motor d remote from the fan drives through a reducer gearing 19 a cylindrical drum member 2d against the periphery of which the feeler 9a is applied. The reducing ratio of gearing i9 is comparatively great so that the drum Ztl is made to revolve quite slowly.

The drum member 2.@ is made of an insulating material and is peripherally coated, towards one of its ends, with a coating of conductive (metallic) material 2l, th'A bounda'y line between the conductive coating 21 and remaining insulating part of the drum periphery bea helix a pitch p. ln other words, along the ircnmference of tie drum member, the length of the cond.. portion of the generatrices of the cylinder is gradually varied from a minimum of a to a maximum of (a-i-p) in one revolution about said drum, and then sharply returns to the value a.

A plug connection 22 is provided for supplying electric current to the motor and to the feeler 9a and therethrough to the conductive portion of the drum, in a manner to be now de cribed with reference to Fig. 3.

As shown in this ligure, the contour Z3 diagrammatically represents the walls of an enclosure in which the temperature is to be adjusted according to the invention. The essential components of the device illustrated in Pigs. l and 2 for accomplishing such temperature adjustment have been illustrated in Fig. 3 in diagrammatic perspective.

A heat-exchanger Zei is provided for maintaining within the enclosure Z3 a temperature higher than that of the external atmosphere. Air from the outer atmosphere enters the enclosure through the inlet 25, if desired under pressure, flows through the annular chamber 2o of the exchanger and enters the enclosure through the aperture 27. The inner chamber of the exchanger is heated by the burner 2 which is fed with combustion air through the conduit 3u having an end inlet 3l, while the burnt gases are discharged from the chamber 2S through the conduit 32. Excess air in the enclosure is discharged therefrom through the conduit 3&3.

Assuming the enclosure 23 to be the cabin of an aircraft moving rightwards of the drawing, it will be noted that the air inlets are all directed in the forward direction while the outlets are directed rearwards of the direction of movement.

The burner 29 is supplied with liquid fuel by an electrically-operated valve controlled by a winding 3S. The valve comprises a conventional needle-valve member 36 for controlling the flow of the fuel, said valve member being made of ferromagnetic material responsive to current flowing through the winding 35,

the 'no o The fuel at the burner nozzle outlet 29 is ignited by electric sparks striking across the igniter gap 37, the necessary ignition current being supplied through the secondary 33 of an igniter coil. The primary 39 of the igniter coil includes a buzzer 4@ provided with contacts 41 shunted by a condenser 42.

The ignition system and the electric valve are fed with D.C. power in parallel from the line leads 43 through the operating contacts 44 of a relay 45. Flow of current through the winding of relay 4S is controlled by the device according to the invention.

For this purpose, the circuit of the winding 45 leads from one side of the line 43, through arm 9, conductive coating 2l on drum 29, a conductor element 46 on the drum connecting said coating with a slip-ring on the drum hub, and brush 47 riding on said ring, to the other side of line 43. The motor 4, not shown in Fig. 3, imparts a slow rotation to the drum and a rapid rotation to the fan 6.

As stated, it is assumed that with the burner 29 operating continuously, the temperature within the enclosure would be maintained at a level higher than that which it is desired to obtain. The air within the enclosure being constrained by the fan 6 to circulate through and around the bi-metal strip 2, the latter assumes a temperature substantially equal to the mean temperature prevailing in the enclosure. Consequently, the bi-metal strip will be subjected to a degree of angular torsion corresponding to said mean temperature and the arm 9 will move in the direction of the arrow F1 if the temperature rises, and in the direction indicated by the arrow F2 if the temperature drops. The feeler 9a applied against the drum periphery contacts the conductive portion 21 at each revolution of the drum for a longer or shorter period of time depending on the angular position of the arm 9 and hence on the temperature prevailing in the enclosure. The arrangement may be seen to be such that the time of contact of feeler 9a with the conductive portion 21 ncreases as the temperature decreases. At the limiting position of the arm 9 in the direction indicated by the arrow F1 the feeler 9a does not engage the conductive coating 21 at all throughout the revolution of the drum 20 and no current flows through the winding 45. Conversely, the arm 9 may be rotated in the direction of the arrow F2 to a position such that current flows continually through the winding 45.

As previously described, the burner 29 is operative only when there is current owing through the winding 4S to energize electro-valve winding 35 and allow fuel to be fed to the burner. Consequently, at each revolution of the drum 2t), the amount of heat supplied by the burner to the exchanger 24 and hence that supplied by the exchanger to the enclosure, depends essentially on the position of the arm 9.

This is visible on the explanatory chart of Fig. 5. In each of the time intervals O-ti ti-tz; zz-ts, etc., the drum 20 completes one revolution. If the position of arm 9 is such that the feeler 9a engages the conductive portion 2l throughout said revolution, the heat output is continuous and the amount of heat supplied permanently to the enclosure may be represented by the horizontal line Q. However, during those revolutions in which the feeler 9a contacts the conductive portion 21 only part of the time, the mean heat output may be represented by horizontal lines such as q1 or q2, the burner operating during the times 0, or 02 respectively and being idle the remainder of the time.

Because of the thermal inertia of the exchanger, the result is that, even though the heating is discontinuous, the temperature of the variably heated air entering the enclosure changes only very gradually. Thus the heat inertia of the exchanger evens out the discontinuous supply of heat from the burner to the exchanger.

It will be noted that, because the boundary line be:

tween the conductive and insulating surfaces of the drum is a helix, the amounts of heat supplied by the burner are substantially proportional to the angular displacements of the arm 9 over the drum, while said angular displacements in turn are substantially proportional to the temperature variations.

It will further be observed that as the drum revolves, the feeler 9a rides continually over its surface. Consequently the friction between the feeler 9a and the drum surface does not impede the angular displacements of the arm 9 under the action of the bi-metal strip 2.

In the modification shown in Fig. 4, the drum 20 is replaced by a disc 48 of insulating material driven in 10- tation through a reducer gearing, and partly coated over its flat surface with a conductive coating 49, the boundary lin between the conductive area 49 and the remaining insulating area of the discs surface being an Archimedean spiral. In the same way as before described, as the arm 9 moves between the end positions 9 and 9, under the control of the bi-metal strip 2, the time of contact between the feeler 9a and the conductive area 49 during each revolution of the disc varies in accordance with the position of the arm and hence with the actual temperature in the enclosure.

By means of the adjusting knob 11 the initial degree of torsion of the bi-metal strip 2 may be varied to vary the amount of heat supplied at each revolution of the revolving member into the enclosure, for a given temperature, and the predetermined constant temperature in the enclosure may thus be adjusted.

The metal coatings 21 and 49 on the revolving insulating member may be produced by local metallization of the surface of the member, or by inlaying a thin metal strip into said surface.

The time required for the revolving member to complete one revolution may be determined in correlation with the thermal inertia of the heat exchanger; the greater the said inertia, the slower may the member be rotated. It will be noted that a quick rotation of the member results in rapid wear of the insulating coating 21 and the feeler 9a. Moreover, if the electric pulses tripping the relay occur at too rapid a rate, the electrically-controlled fuel valve may be unable to respond.

If the rotation is too slow on the other hand, the heat exchanger may be subjected to large temperature variations which impair its service life, and moreover the air is discharged from the exchanger at a rapidly variable temperature. As a practical indication, satisfactory results have been obtained with the device when the revolving drum or disc is rotated at a rate of from 3 to 10 seconds per revolution.

It can further be indicated that the sensitivity of the device is so high that the total amplitude of movement of the arm 9 may be obtained for a tempearture variation of only 2 C., so that the desired temperature adjustment may easily be obtained to within plus or minus 1/2 C.

It is to be` expressly understood that many details of the apparatus described and illustrated may be modified and substituted by equivalent ones without departing from the scope of the invention as defined in the ensuing claims.

What I claim is:

l. Air-conditioning device for keeping the temperature of air supplied by an electrically controlled air-heater at a predetermined level comprising in combination an electric pulse generator having a rotary member bearing on a surface thereof adjacent conductive and insulating areas of such design that the length of one relative to that of the other, as measured along successive circles of said surface concentric with the rotation axis of said member, progressively varies, and a conductive feeler displaceable about said surface and permanently engaging same to be positioned on one of said circles, whereby on rotation of said member, said feeler comes successively into con- .tact With .Said Conductive and insulating areas; an electric control circuit for said air-heater, extending through said conductive area and said feeler; a bi-metal strip subjected to said air temperature and drivingly connected to said feeler for displacing same along said surface transversely of said circles as said bi-rnetal strip is distorted in response to variation of said air temperature; a fan drawing air about said bi-rnetal strip; a casing inside which said pulse generator, bi-metal strip and fan are located, said casing being provided with air inlet and outlet passages; and a rotary motor, inside said casing, having a two-ended drive shaft, said fan being driven from one end of said shaft and said rotary member being driven from the other end of said shaft.

2. Device as claimed in claim 1, wherein said bi-metal strip is of helical formation and of generally tubular shape, air being drawn through and around said strip by said fan.

3. Device as claimed in claim 1, wherein said surface is at and the boundary line between the adjacent conductive and insulating areas is substantially a single-turn Archimedean spiral, said feeler being displaceable generally radially of said spiral.

6 4. Device as claimed in claim 1, wherein said surface is cylindrical and the boundary line between the adjacent conductive and insulating areas is substantially a singleturn helix, said feeler being displaeeable generally along a generatrix of said cylindrical surface.

References Cited in the le of this patent UNITED STATES PATENTS 

